Four people have been arrested on suspicion of murder following an incident on Stokesley High Street in the early hours of Saturday 14 May 2011.
North Yorkshire Police were called at around 12.05am after reports that a man had been seriously assaulted outside College Pizzas in College Square.
The victim, aged 17, from Stokesley, suffered a head injury in the incident and was taken to James Cook hospital for treatment. Unfortunately, he never recovered from his injuries and was pronounced dead at around 2.50am.
Officers are appealing for any witnesses to the incident to come forward with information.
Detective Superintendent Lewis Raw, of North Yorkshire Police, said: “A charcoal-coloured Volkswagen Polo, which has been seized by police, is believed to be connected to the incident and we would like to speak to anyone who saw that vehicle in the area at the time of the incident.
“I would also appeal to anyone who witnessed the incident itself to contact the police or Crimestoppers with information.”
The four people arrested are two 17-year-old men from Guisborough and a 25-year-old man and a 17-year-old woman from Middlesbrough.
They remain in police custody as enquiries continue.
Anyone who can help the police with the investigation is urged to contact Northallerton CID, on 0845 60 60 24 7, quoting reference number 12110078100.
Alternatively, Crimestoppers can be contacted anonymously on 0800 555 111.